Think that's all good advice up there. Paint those colours over a white base and/or primer. Barring that, thinning them more than usual and doing more layers than usual will help to smooth out and give good coverage. The more you thin it the less time you need to wait to let it dry enough for the next layer too, so it evens out, sorta.
Another related tip, white covers, and also white helps cover, in other words, if you want to cover the colour below, mix in some white to the top colour. Painting red over pink, painting yellow over a "pastel" yellow. If you get a nice white primer it'll cover even better but tends to be grainier. Anyway, mixing white in the "in between" layer works like a charm %99 of the time.
I don't know enough about the foundation paints to say for sure, but they might hurt more than help you progress (in the long run).